If Two Sources of Slightly Different Frequency and Different Amplitudes

If two sources of slightly different frequency and different amplitudes create waves at the same time, the resulting superposition of those waves can be described as

A) a wave with an amplitude that varies from zero to an amplitude equal to the sum of individual amplitudes. This variation would occur at a frequency equal to the difference in source frequencies.
B) a standing wave with an amplitude equal to the average of the amplitudes of the individual waves and a frequency equal to the average of individual frequencies.
C) a wave with an amplitude that varies from an amplitude of the difference in individual amplitudes to an amplitude equal to the sum of individual amplitudes. This variation would occur at a frequency equal to the difference in source frequencies.
D) a standing wave with an amplitude equal to the sum of the amplitudes of the individual waves and a frequency equal to the average of individual frequencies.
E) a standing wave with an amplitude equal to the product of the amplitudes of the individual waves and a frequency equal to the sum of individual frequencies.